If they [Constructs] die then they die, they won't be loose; having un-manned Constructs means the player failed to come out before they lost all their Willpower, either because they slacked or the DPS didn't do enough DPS.

Our tank is saying DPS killed him and thats what caused the loose ones... is this possible?

that should kill both the tank and the construct, haven't had that happen in a long time though.
Chances are is he's just trying to stay in the vehicle too long before getting out. You really need to get out of the vehicle at latest 5 willpower because of latency and other issues. If you had logs it might be possible to see what happens.